Conventional starters for starting internal combustion engines normally include a pinion movable between an engagement position and a disengagement position. When the pinion is located at the engagement position, the pinion is engageable with a ring gear rotatable together with a crankshaft of an internal combustion engine. When the pinion is located at the disengagement position, the pinion is disengaged with the ring gear.
The conventional starters also include an actuator configured to shift the pinion from the engagement position to the disengagement position when energized. The conventional starters further include a motor for rotating the pinion when energized.
In view of improve, for example, drivability, control systems for controlling such a starter are required to restart, as immediately as possible, an internal combustion engine that has been stopped. Particularly, these requirements are increased when these control systems are installed in motor vehicles for automatically stopping their internal combustion engines during the motor vehicles being temporarily stopped.
In order to meet these requirements, control systems for these starters are designed to carry out so-called “preset control” or so-called “pre-rotation control” described hereinafter.
The “preset control” is proposed to mainly assume that an engine start request occurs during an internal combustion engine, referred to simply as “engine”, being stopped. Specifically, the preset control is to shift the pinion to the engagement position prior to the occurrence of an engine start request, and to hold the pinion at the engagement position. Thereafter, when an engine start request occurs, the preset control is to rotate the pinion to thereby crank the engine. The preset control can start the engine more rapidly as compared to control to shift the pinion to the engagement position in response to the occurrence of an engine start request.
The “pre-rotation control” is proposed to mainly assume that an engine start request occurs during the rotational speed NE of the crankshaft of the engine being reduced. Specifically, the pre-rotation control is to rotate the pinion before the rotational speed NE reaches zero, and thereafter to shift the pinion to the engagement position so as to mesh the pinion with the turning ring gear. The pre-rotation control can start the engine more rapidly as compared to control to wait for the rotational speed NE to reach zero after the occurrence of an engine start request, and to engage the pinion with the ring gear.
In order to carry out the preset control and the pre-rotation control, control systems for starters are required to independently control shift of the pinion to the engagement position and rotation of the pinion.
In order to meet such requirements, US Patent Application Publication No. 2008/0127927 corresponding to WO Publication No. 2006/018350 and to Published Japanese translation No. 2008-51009 of the WO Publication No. 2006/018350 discloses a starter control system provided with a first MOS switch (first switch unit) for switching energization and deenergization of the actuator and with a second MOS switch (a second switch unit) for switching energization and deenergization of the motor. Similarly, WO Publication 2006/120180 corresponding to Published Japanese translation No. 2009-500550 thereof discloses the first and second MOS switches.